3D Adaptive Stiffness Isolator for Seismic Displacement Control
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Solution Overview
Problem
Traditional seismic isolators fail to effectively reduce vertical earthquake and environmental vibration components, and they face a trade-off between isolation effectiveness and displacement, where improved isolation can lead to excessive displacement during earthquakes.
Innovation Solution
A three-dimensional isolator with adaptive stiffness, comprising a combination of disc springs, helical springs, laminated lead rubber bearings, pre-stressed helical springs, and viscous dampers, which provides quasi-zero stiffness in the vertical direction and adaptive stiffness in the horizontal direction to isolate seismic and environmental vibrations independently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a soft isolation layer is designed to extend the natural period for better isolation effect, then the horizontal seismic isolation performance is improved, but the isolation displacement becomes excessively large
Solution Approach 1:
The isolator employs adaptive stiffness characteristics where the horizontal stiffness changes dynamically with displacement magnitude. At small displacements, the stiffness is soft to achieve good isolation effect, while at large displacements, the stiffness becomes hard to limit the maximum displacement. This is achieved through the nonlinear mechanical properties of the lead rubber bearing and the geometric nonlinearity of the spring system.
Solution Approach 2:
The system changes its stiffness parameter based on the operating conditions. The lead rubber bearing provides different stiffness characteristics at different strain levels, and the pre-stressed springs modify the overall stiffness profile. This parameter change allows the system to optimize both isolation performance and displacement control under varying earthquake intensities.
2Reliability
If viscous dampers and pre-stressed springs are added to achieve adaptive stiffness, then isolation performance is improved, but device complexity increases
Solution Approach 1:
The isolator merges multiple functional components into a single integrated device. The lead rubber bearing, disc springs, helical springs, and viscous dampers are combined in a unified structure that provides both horizontal and vertical isolation with adaptive stiffness. This merging approach achieves superior isolation performance while avoiding the need for separate isolation systems for different directions and conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The adaptive stiffness system effectively isolates vertical and horizontal vibrations, ensuring safety by controlling excessive displacement and providing superior isolation performance compared to traditional methods, while dissipating motion energy in both directions.
Implementation Method 1
the disk spring can provide negative stiffness and helical spring provides positive stiffness. Thus, the vertical isolation system can have a quasi-zero stiffness property
Implementation Method 2
the disk spring can provide negative stiffness and helical spring provides positive stiffness. Thus, the vertical isolation system can have a quasi-zero stiffness property
Implementation Method 3
The pre-stressed helical spring can provide negative stiffness when the horizontal displacement is small but positives stiffness when the horizontal displacement is large. The horizontal isolation system is characterized by adaptive stiffness by adding the pre-stressed helical spring.
Implementation Method 4
the viscous dampers and lead core are added to dissipate the motion energy in both vertical and horizontal directions
Implementation Method 5
An inner lead core is designed at the center of the laminated lead rubber bearing to dissipate motion energy in horizontal and vertical directions
Data Source
AI summary
The present disclosure discloses a three-dimensional seismic and vibration isolator with adaptive stiffness property in both vertical and horizontal directions. The isolator comprises an upper connection plate, a middle plate, an lower connection plate, a disc spring, a pre-compressed helical springs, a laminated lead rubber bearing, and viscous dampers. The upper connection plate, the middle plate and lower connection plate are made of high strength low carbon steel. The upper connection plate and middle plate are tightly contacted by the occlusive design, to guide the vertical motion. The vertical isolation system is made up of the disc spring, pre-compressed helical spring, and viscous damper. The horizontal isolation system comprises the laminated lead rubber bearing, pre-compressed helical spring and viscous damper. The disclosure adopts the theory of nonlinear adaptive vibration control technology and can be used to protect building structures or instruments from the seismic strikes or other environmental vibrations.